On Tuesday, the mayor promised small-business owners relief from onerous city fines. But the very next day, he pushed a bill that will sock these businesses with hefty new costs in the form of sick-leave pay.

Here’s what he said Tuesday when he named Maria Torres-Springer as his new small-business commissioner: “For too long, the central relationship between small business and the city government has been when an inspector walks through the door of that small business ready to issue a fine. . . Maria’s going to help change that.”

Cue the applause. Ending the city’s practice of making up revenue gaps by fining businesses would help fulfill a key de Blasio campaign vow — and offer a bit of sanity to the thousands of New Yorkers struggling to run their cafes, bodegas, retail shops, start-ups and other small enterprises. The mayor rightly noted that immigrant-owned businesses and those in the outer boroughs would especially benefit.

Then came Wednesday, when he turned around to push a bill that would make it harder for these folks to succeed. Even very small businesses — those with as few as five workers — would be forced to provide up to five paid sick days a year for each employee.

No matter how strapped these owners find themselves. No matter how badly the workers need the jobs. No matter how eager they are to take these jobs without the sick-leave pay.

De Blasio claims the bill “will improve the lives of thousands of this city’s working people and their families.” Workers, he says, will no longer lose pay, or perhaps their jobs, if they get sick.

Small-business owners say otherwise: “Having employees take off and still be paid — that will push us over the edge,” one restaurateur, Rakan Ammouri, told Crain’s. “You got to be kidding me,” says Doreen Zayer, owner of a Staten Island massage-therapy business. “They just put me out of business.”

The sick-leave law is expected to sail through the council. If Torres-Springer really wants to make a difference for New York’s small businesses, maybe she should have a word with the mayor about that.